Mu4e is designed to enable super-efficient handling of e-mail; searching, reading, replying, moving, deleting. It sits on top of your Maildir (which you update with e.g. offlineimap or fetchmail).

Under the hood, mu4e is fully search-based, similar to programs like notmuch, md and sup. However, mu4e's user-interface is quite different. mu4e's mail handling (deleting, moving etc.) is inspired by Wanderlust [another emacs-based e-mail client, famously hard to get working], mutt and dired.

mu4e tries to keep all the 'state' in your maildirs, so you can easily switch between clients, synchronize over IMAP, backup with rsync and so on. If you delete the database, you won't lose any information.

Features include:

Fully search-based: there are no folders, only queries

UI optimized for speed with quick key strokes for common actions

Fully documented, with example configurations

Asynchronous: heavy actions never block emacs

Write rich-text e-mails using org-mode (experimental)

Address auto-completion based on your messages – no need for managing address books